Like any red-blooded American, I find regex golf fascinating. The idea, to
paraphrase the comic strip, is to find a regular expression that matches all members of a group of related terms, but not
any members of a different group. The hover text on the strip suggests a regex that matches all winning presidents.

Peter Norvig went to town on this,
first clarifying the
problem and then building an algorithm to search for the shortest
solution that matches all mainstream presidential candidates who eventually
won, but not such candidates who never won. (So Perot, Nader, Anderson et al don't figure …